Part 1
Seats
Pinpoint Test AJ: DTC B272A
Normal Operation
Climate controlled seats are independently controlled by the Dual Climate Controlled Seat Module (DCSM) mounted to the bottom of the passenger seat cushion. The climate controlled seat system only operates with the engine running, however, if using a scan tool to command the DCSM (Dual Climate Controlled Seat Module), diagnostic testing can be carried out with the ignition ON. The system receives voltage from Battery Junction Box (BJB) fuse 22 (30A) supplying voltage into DCSM (Dual Climate Controlled Seat Module) C3265a pins E and F, circuit CBX01 (GN/RD). If voltage is disconnected from either pin E or F of DCSM (Dual Climate Controlled Seat Module) C3265a both seats will remain operational because the voltage supply circuits are connected internally in the DCSM (Dual Climate Controlled Seat Module). However, if a fault occurs setting a DTC specific to either climate controlled seat, only the affected seat will be disabled by the DCSM (Dual Climate Controlled Seat Module).
The seat cushion and backrest are equipped with a Thermo-Electric Device (TED) assembly that includes a seat blower (fan motor, serviced as an assembly with the TED (Thermo-Electric Device)). Cabin air is drawn through the blower and distributed to each of the TED (Thermo-Electric Device) modules. The TEDs (Thermo-Electric Devices) then heat or cool the air. The air is then directed into the foam pad and manifold where it is distributed along the surface of the cushion and backrest of the seat. Once the system is activated, the DCSM (Dual Climate Controlled Seat Module) uses a set of flexible algorithms to control the heating/cooling modes and the blower speed dependant on the HVAC module seat switch settings.
- DTC B272A (Passenger Cushion Over-Temp Detected)- In the cooling mode, if the passenger seat cushion TED (Thermo-Electric Device) temperature exceeds 70°C (158°F) for more than 34 seconds, the TED (Thermo-Electric Device) is disconnected or the duct is blocked, the DCSM (Dual Climate Controlled Seat Module) will shut down the passenger seat system and set this DTC.
- DTC B272A (Passenger Cushion Over-Temp Detected)- In the heating mode, if the passenger seat cushion TED (Thermo-Electric Device) temperature exceeds 85°C (185°F) for more than 34 seconds, the TED (Thermo-Electric Device) is disconnected or the duct is blocked, the DCSM (Dual Climate Controlled Seat Module) will shut down the passenger seat system and set this DTC.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Restricted cushion TED (Thermo-Electric Device) filter
- Crushed or restricted cushion foam pad
- Crushed or restricted climate controlled seat manifold
- Cushion TED (Thermo-Electric Device) assembly
- DCSM (Dual Climate Controlled Seat Module)
PINPOINT TEST AJ : DTC B272A
NOTICE: When taking measurements at Dual Climate Controlled Seat Module (DCSM) harness connectors, do not insert the electrical probes into the female connector pins. Inserting the probes into connector pins can cause intermittent or open electrical connections after reassembly resulting in Diagnostic Trouble Codes (DTCs) and system failure. Touching the tip of these connector pins is recommended instead.
NOTE: The air bag warning indicator illuminates when the correct Restraints Control Module (RCM) fuse is removed and the ignition is ON.
NOTE: The Supplemental Restraint System (SRS) must be fully operational and free of faults before releasing the vehicle to the customer.
AJ1 CHECK THE DCSM (Dual Climate Controlled Seat Module) FOR ON-DEMAND DTCs
- Start the vehicle and set the passenger seat to HIGH heat.
- Enter the following diagnostic mode on the scan tool: Self Test- DCSM (Dual Climate Controlled Seat Module).
Was DTC B272A retrieved on-demand during the self-test?
Yes
GO to AJ2.
No
GO to AJ5.
AJ2 CHECK THE PASSENGER SEAT CUSHION TED (Thermo-Electric Device) THERMISTOR CIRCUITS FOR A SHORT TO GROUND
- Ignition OFF.
- Depower the SRS (Supplemental Restraint System). Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of Restraints and Safety Systems &/or Air Bag Systems.
- Disconnect: Passenger Seat Side Air Bag C3133.
- Disconnect: Passenger Seat Safety Belt Buckle Pretensioner C3066.
- Disconnect: DCSM (Dual Climate Controlled Seat Module) C3265B.
- Disconnect: Passenger Seat Cushion TED (Thermo-Electric Device) C3040.
- WARNING: Make sure no one is in the vehicle and there is nothing blocking or placed in front of any air bag module when the battery is connected. Failure to follow these instructions may result in serious personal injury in the event of an accidental deployment.
Connect the battery ground cable.
- Measure the resistance between:
- DCSM (Dual Climate Controlled Seat Module) C3265B-2, circuit VHS27 (WH/OG), harness side and ground.
- DCSM (Dual Climate Controlled Seat Module) C3265B-3, circuit RHS10 (BU/OG), harness side and ground.
Are the resistances greater than 10,000 ohms?
Yes
GO to AJ3.
No
REPAIR the circuit(s). CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
AJ3 CHECK THE PASSENGER SEAT CUSHION TED (Thermo-Electric Device) THERMISTOR AND WIRING
- Connect: Passenger Seat Cushion TED (Thermo-Electric Device) C3040.
- Measure the resistance between DCSM (Dual Climate Controlled Seat Module) C3265B-2, circuit VHS27 (WH/OG), harness side and DCSM (Dual Climate Controlled Seat Module) C3265B-3, circuit RHS10 (BU/OG), harness side. Note the ambient temperature and refer to the following table.
Temperature Resistance 0-10°C (32-50°F) 2,782-1,663 ohms 10-20°C (50-68°F) 1,837-1,140 ohms 20-30°C (68-86°F) 1,260-806 ohms 30-40°C (86-104°F) 893-570 ohms 40-50°C (104-122°F) 630-428 ohms
Is the resistance within the limits indicated?
Yes
GO to AJ18.
No
GO to AJ4.
AJ4 CHECK THE PASSENGER SEAT CUSHION TED (Thermo-Electric Device) THERMISTOR
- Disconnect: Passenger Seat Cushion TED (Thermo-Electric Device) C3040.
- Measure the resistance between passenger seat cushion TED (Thermo-Electric Device) C3040 pin 5 and pin 8, component side. Note the ambient temperature and refer to the following table.
Temperature Resistance 0-10°C (32-50°F) 2,782-1,663 ohms 10-20°C (50-68°F) 1,837-1,140 ohms 20-30°C (68-86°F) 1,260-806 ohms 30-40°C (86-104°F) 893-570 ohms 40-50°C (104-122°F) 630-428 ohms
Is the resistance within the limits indicated?
Yes
REPAIR circuit VHS27 (WH/OG) or RHS10 (BU/OG) for an open or high resistance. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
No
INSTALL a new passenger seat cushion TED (Thermo-Electric Device). REFER to Seat Cushion Thermo-Electric Device . CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
AJ5 CONFIRM THE FAULT WHILE MONITORING THE DCSM (Dual Climate Controlled Seat Module) SEAT BACK THERMAL ELECTRIC DEVICE TEMPERATURE (PBKTEMP) AND SEAT CUSHION THERMAL ELECTRIC DEVICE TEMPERATURE(PCSHTEMP) PIDs
- Set the passenger seat to OFF.
- Enter the following diagnostic mode on the scan tool: Clear DTCs - DCSM (Dual Climate Controlled Seat Module).
- Enter the following diagnostic mode on the scan tool: DataLogger - DCSM (Dual Climate Controlled Seat Module).
- Monitor the DCSM (Dual Climate Controlled Seat Module) PIDs PBKTEMP and PCSHTEMP.
- NOTE: A crushed seat cushion foam pad or a crushed climate controlled seat manifold may be the cause of the fault making it necessary to occupy the seat to recreate and identify the fault.
Attempt to recreate the fault. Start the vehicle and set the passenger seat to HIGH heat for at least 15 minutes while occupying the seat.
Do the PIDs increase incrementally (gradually) and stay within 15°C (27°F) of each other?
Yes
Fault not present at this time. Fault may have been set due to a past failure, incorrect use of the climate controlled seat system by repeated switching between heat and cool modes or due to excessive passenger compartment temperature. CLEAR the DTCs. REPEAT the self-test.
No
If the PCSHTEMP PID increases incrementally and is greater than 15°C (27°F) of the PBKTEMP PID, GO to AJ6.
If the PCSHTEMP PID increases quickly (temperature "jumps" and does not increase incrementally) and is greater than 15°C (27°F) of the PBKTEMP PID, GO to AJ16.
AJ6 COMPARE OPERATION OF THE DRIVER AND PASSENGER SEATS
- With the engine running, set both front seats to HIGH cool.
- Note the airflow exhausting from the passenger seat cushion TED (Thermo-Electric Device) and compare it to the airflow exhausting from the driver seat cushion TED (Thermo-Electric Device).
- Carry out a wiggle test of the wire harnesses between the DCSM (Dual Climate Controlled Seat Module) and the passenger seat cushion TED (Thermo-Electric Device) while monitoring blower operation of the TED (Thermo-Electric Device). The blower should operate consistently and not change speeds
Is the airflow exhausting from the passenger seat cushion TED (Thermo-Electric Device) comparable to the airflow exhausting from the driver seat cushion TED (Thermo-Electric Device) with no change in operation when carrying out the wiggle test?
Yes
GO to AJ7.
No
If the airflow exhausting from the passenger seat cushion TED (Thermo-Electric Device) is not comparable to the airflow exhausting from the driver seat cushion TED (Thermo-Electric Device), GO to AJ8.
If the passenger seat cushion TED (Thermo-Electric Device) blower operation changed while carrying out the wiggle test, IDENTIFY and REPAIR the wiring fault. CLEAR the DTCs. REPEAT the self-test.
AJ7 COMPARE OPERATION OF THE DRIVER AND PASSENGER SEATS WHILE OCCUPIED
- Note the airflow exhausting from the passenger seat cushion TED (Thermo-Electric Device) with the passenger seat occupied and compare it to the airflow exhausting from the driver seat cushion TED (Thermo-Electric Device) with the driver seat occupied.
Is the airflow exhausting from the passenger seat cushion TED (Thermo-Electric Device) comparable to the airflow exhausting from the driver seat cushion TED (Thermo-Electric Device)?
Yes
GO to AJ16.
No
INSTALL a new passenger seat cushion foam pad and/or climate controlled seat manifold. CLEAR the DTCs. REPEAT the self-test.
AJ8 CHECK THE PASSENGER SEAT CUSHION BLOWER FOR AN OBSTRUCTION OR RESTRICTED FILTER
- Ignition OFF.
- Inspect the blower of the passenger seat cushion TED (Thermo-Electric Device) assembly for an obstruction or for a restricted filter.
Is the blower obstructed or the filter restricted?
Yes
REMOVE the obstruction or INSTALL a new filter. CLEAR the DTCs. REPEAT the self-test.
No
GO to AJ9.
AJ9 CHECK THE PASSENGER SEAT CUSHION BLOWER SPEED CONTROL CIRCUIT FOR AN OPEN
- Depower the SRS (Supplemental Restraint System). Refer to Supplemental Restraint System (SRS) Depowering and Repowering in the General Procedures portion of Restraints and Safety Systems &/or Air Bag Systems.
- Disconnect: Passenger Seat Side Air Bag C3133.
- Disconnect: Passenger Seat Safety Belt Buckle Pretensioner C3066.
- Disconnect: DCSM (Dual Climate Controlled Seat Module) C3265C.
- Disconnect: Passenger Seat Cushion TED (Thermo-Electric Device) C3040.
- WARNING: Make sure no one is in the vehicle and there is nothing blocking or placed in front of any air bag module when the battery is connected. Failure to follow these instructions may result in serious personal injury in the event of an accidental deployment.
Connect the battery ground cable.
- Measure the resistance between DCSM (Dual Climate Controlled Seat Module) C3265C-3, circuit VHS23 (BN/BU), harness side and passenger seat cushion TED (Thermo-Electric Device) C3040-7, circuit VHS23 (BN/BU), harness side.
Is the resistance less than 5 ohms?
Yes
GO to AJ10.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
AJ10 CHECK THE PASSENGER SEAT CUSHION BLOWER CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between DCSM (Dual Climate Controlled Seat Module) C3265C-7, circuit RHS08 (VT/WH), harness side and ground.
Is any voltage present?
Yes
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
DISCONNECT the battery ground cable. CONNECT passenger seat side air bag module C3133.
CONNECT passenger seat safety belt buckle pretensioner C3066.
REPOWER the SRS (Supplemental Restraint System). REFER to Restraints and Safety Systems &/or Air Bag Systems.
No
GO to AJ11.